New York City's first cases of West Nile Virus of the season have survived while two more persons in San Joaquin County contracted the virus. Health officials say more mosquitoes have been tested positive for the virus this year.

The county’s first human case of the year was a 46-year-old south county man who developed West Nile Neuro-invasive disease. This is the most serious condition of infection from the virus and approximately one in 150 people infected with the virus develop this severe condition. The serious and rare form of the disease can result in permanent neurological damage and can be fatal.

About a fifth of people infected with the virus develop West Nile fever. County Public Health Department says the symptoms include headache, fever and fatigue, though most people who get infected with the disease don’t get sick at all.

County Public Health Officer Karen Furst said, “All blood banks in the United States are screened for West Nile.”

The New York City health department is urging people to take necessary precautions like wearing bug spray while outdoors.